The unit of spectral energy fluence rate is

Correct option is D

✅ (d) W m⁻² nm⁻¹ [Spectral Fluence Rate Unit] • Spectral energy fluence rate represents the energy of light delivered per unit area, time, and wavelength. • Measured in Watts per square meter per nanometer (W m⁻² nm⁻¹). • Important in photosynthesis and light-related plant physiology studies.
❌ (a) mol photon m⁻² s⁻² nm⁻¹ • Unit is inconsistent (incorrect exponent on s).
❌ (b) J m⁻² s⁻¹ • Unit of irradiance, not spectral fluence rate.
❌ (c) mol m⁻² s⁻¹ • Unit of photon flux density, not energy fluence.